package com.kuang.servlet;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.URLEncoder;

/**
 * Author: Zhang Dongwei
 * Date: 2022/4/17 8:53
 */
public class FileServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        1. 获取下载文件的路径
        String realPath = "D:\\Code\\Java\\JavaWeb03\\response\\target\\classes\\1.png";
        System.out.println("下载文件的路径："+realPath);
//        2. 下载的文件名是啥？
        String filename = realPath.substring(realPath.lastIndexOf("\\") + 1);
//        3. 设置想办法让浏览器能都支持我们下载的东西 文件名是中文的时候，可以设置URLEncoder.encode(fileName, “UTF-8”)，否则有可能乱码
        resp.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename, "UTF-8"));
//        4. 获取下载文件的输入流
        FileInputStream in = new FileInputStream(realPath);
//        5. 创建缓冲区
        int len = 0;
        byte[] buffer = new byte[1024];
//        6. 获取OutputStrem对象
        ServletOutputStream out = resp.getOutputStream();
//        7. 将FileOutputStream流写入到buffer缓冲区,使用OutputStream将缓冲区中的数据输出到客户端
        while ((len=in.read(buffer))>0){
            out.write(buffer, 0, len);
        }
//        8. 关闭流
        in.close();
        out.close();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}
